Season Preview: Explaining the Flames Power Play Improvement

(One sometimes overlooked aspect of the Flames big turn around last year was their improvement on the man advantage. The club went from bottom-third to top-10 very rapidly. I asked JaredL of the excellent analytic blog Driving Play to investigate whether that improvement was due to luck, ability or circumstance and what it might portend for this year. This is what he found)

By: JaredL

Kent asked me to step away from my usual home at Driving Play to write an article on the Flames’ improvement on the power play last season. Analyzing special teams is a tricky business, much more so than even-strength play. The sample sizes are drastically smaller; the Flames averaged over 49 minutes per game at even strength compared to about 6:25 on the power play and 5:42 killing penalties. They are also irregular – one game you might be on the power play just once and another you might get 10 opportunities. Despite all that, we can use shooting stats to get some insight into what was going on out there.

A Tale of Two Halves

The Flames’ power play struggled early on and steadily improved over the season. Here is a graph of their power play percentage and their scoring rate on the power play, over the course of the season. You can see that they got better as the season went on, as shown by the general upward trend in the graphs.

There was a massive difference between the first and second half of the season. Here’s a table with their results by half:

Half

Goals

PP%

PPG/60 mins

First

25

0.152

5.692

Second

37

0.243

8.724

Possible Explanations

Here are some possible explanations:

1. They had more short or broken-up power plays in the first half, leading to a lower percentage.

2. They had more 5-on-3 power plays late in the season.

3. They faced tougher penalty-killing teams earlier in the season than late.

4. Later in the season they did better at getting setup in the offensive zone and dominating possession.

5. They created better shots and/or more of their shots went in as the season went on. Let’s look at these individually.

1. They had more short or broken-up power plays in the first half, leading to a lower percentage.

I eliminated this with the above table. Their rate went up in almost the same pattern as their power-play percentage, so it does not appear to be some fluke in the timing of power plays. While in theory PP% might be the most obviously flawed metric in sports, it does have a very strong correlation to scoring rate as you can see, so it’s fine to use in practice.

2. They had more 5-on-3 power plays late in the season.

This is pretty easy to reject. Here’s a table of 5-on-3 goals and opportunities in the two halves of the season:

Half

Goals

Opportunities

First

2

0.09

Second

4

0.06

3. They faced tougher penalty-killing teams earlier in the season than late.

It’s tough for the schedule to get drastically tougher over half of a season, but if Calgary faced a bunch of cupcakes late then that could lead to these results. This does not appear to be the case, in fact, it looks like the opposition was ever-so-slightly better on the penalty kill in the second half of the season. Here’s a table with the average penalty kill percentage of the Flames’ opponents in each half. The first column is the raw average, the second weighted by the number of chances Calgary had in the game:

Half

Avg. PK%

Weighted Avg. PK%

First

81.3%

81.2%

Second

81.4%

81.8%

Looking at their opponents’ PK% gives us another way to see the Flames’ improvement. Here are two line graphs, one for each half of the season, showing how Calgary fared compared to what their numbers would have been if they’d scored at the average percentage their opponents allowed:

Over the first half of the season, the Flames scored 6.07 goals below average when you take opponent PK% into account. That flipped in the second half – they had 9.3 more PP goals than average.

4. Later in the season they did better at getting setup in the offensive zone and dominating possession.

The standard way to measure possession and territorial dominance is Corsi stats. Corsi is like +/- but includes all types of shots – goals, saved shots, missed shots and blocked shots. Since we’re looking at the power play only, it might be useful to ignore the minus aspect and just look at all the shots the Flames generated. I call this +Corsi. Here is a table with their Corsi rate and +Corsi rate over each half of the season:

Half

Corsi Rate

+Corsi Rate

First

74.288

90.923

Second

78.810

94.855

As you can see, the Flames did improve in territorial dominance. They improved their overall Corsi by about 6% (4.3% if you focus only on their own shots). Using back-of-the envelope calculations, I estimate that about 1.3 goals of their second-half improvement is due to bettering their +Corsi.

5. They created better shots and/or more of their shots went in as the season went on.

First let’s focus on the second part. The main reason that the Flames improved so much was that a higher percentage of their shots hit the back of the net. Here is a table with their goals, shots and shooting percentage for each half:

Half

Goals

Shots

Shooting%

First

25

208

12.0%

Second

37

218

17.1%

Both halves were more extreme than their best and worst PP shooting percentages for all seasons since the lockout. It’s pretty clear that luck played a big role on both sides – the Flames were unlucky to shoot so poorly in the first half of the season and fortunate to shoot so well in the second. Did they create better shots, though? There is some evidence of that. While exact shot location would be better, a decent, and much quicker, way to look at the quality of shots is to look at distance. Here is a table breaking down the number of shots, including missed shots, they took from each distance range:

Distance (ft.)

1st Half

2nd Half

0-10

29

33

11-15

33

39

16-20

21

25

20-25

16

25

26-30

21

22

31-35

20

20

36-40

32

20

41-45

23

36

46-50

33

35

51-55

29

23

56-60

21

31

>60

12

8

Total

290

317

And here that is in bar-chart form:

You can see that they did a much better job getting into dangerous areas for their shots. The Flames took 27 more shots on the power play in the second half of the season and an impressive 24 of those extra shots were from inside of 30 feet. While I think most of their improvement came down to luck, given that a higher percentage of their shots came from closer range it’s clear that they were getting better shots and that was responsible for part of their improved shooting percentage.

What does that mean for 2011-2012?

Power Play performance is tough to analyze and tougher still to predict. The good news for Flames fans is that things definitely went the right direction and it wasn’t all luck. It’s clear that Calgary was on the wrong side of the bounces earlier on and were overly fortunate later. I don’t expect the Flames to shoot quite as high a percentage as they did but they should still be one of the better teams on the power play. Somewhere around 10th in PP% seems reasonable if they can continue to sustain their second half shot rates and such.

(Thanks again to JaredL for doing such great work. Check out Driving Play for similar quality quantatitive analysis.)

19 Comments |

Really interesting to see the Analytics behind a PP in general. Thanks guys, I have a question about the effect that Babchuck had on the PP. While, it’s overly simplistic to think one guy changed the fortunes of the Flames PP last year, there is no question the threat of having Babs on the Blue line was a big bonus for the team. All the PK’s had move up towards him to protect against the heavy shot from the blue line, which meant opening up room down low. I think this might explain why the stats are showing more shots between 40- 60 feet, as well as under 25 feet from the net.

Babchuk’s shots for while on the ice with the Flames on the PP was 41.3/60. His shots for off was actually 43.0, meaning shots went down with him on the ice. His relative 5-on-4 corsi was -4.3…the worst amongst regular PP defenders.

Babchuk’s goals for on last year was 6.53/60…goals for off the ice? 7.16. So, again, his club’s managed to do a bit more with him on the bench.

Your conclusion was an intuitive one since his arrival and the Flames PP improvement pretty happened in unison. Plus, he’s mostly a PP specialist. The info we have from last year suggests he’s not really the guy driving the bus though.

That’s not to say I’d take him off the PP or anything, of course.

EDIT to add – Babchuk’s stats are a little sullied by his time in CAR, so I should note it’s possible he had really rotten relative metrics due to, say, being on their second PP unit which may have stunk. Nevertheless, I think we should see better results if Babchuk truly were a PP dynamo, but it would be instructive if we could parse his CGY results from his CAR ones.

PP is different ballgame though. It’s never “good” to be a poor skater, but it’s far less of an impediment on the man advantage.

The dude has averaged about 4PPP/60 during his time in the NHL. That’s not elite, but it’s decent. I think he’s a worthwhile addition to the PP – I’m just dubious that he was the reason the Flames PP took off last year.

I guess you would have to go PP by PP and shot by shot, but I would be damn interested to know how much of the improvement in shooting percentage is directly attributable to Babchuk scoring. I would have to Google around (as behindthenet.ca only has season totals) but I was under the impression Babchuk had a crazy high personal shooting percentage on the power play after he got to the Flames.

I suspect the Flames powerplay success this season may driven by how far he regresses to the mean in shooting percentage.

yeah – it’s never a bad thing to have that booming shot, or that threat of a booming shot coming in from the blueline. Opens up the ice a little..unless your that poor sap who has to stand in front of the net and screen

Goals are obviously an important stat to measure, but so are assists and other events that are harder to measure. To me Babchuck’s shot forces PK’ers to move toward the Blue line, thereby opening up the middle of the ice. My impression is that the as he began to shoot more, both the shots at +40 feet and inside of 25 feet went way up int the second half of the year.

There is no way that Babs is the sole reason for the Flames improvement. I thought there was an improvement on both PP units by most of the players, especially in terms of keeping the puck in the OZ, and moving it around for better opportunities. I believe, that Babs was a significant weapon on the point that PK’ers needed to address, and he was one of several factors for the improvement.

Let’s see how he does this year and what I’m really afraid of let’s see how many shorthanded goals can be blamed on his foot-speed.

Judging by the first graph alone, one might be inclined to think that there was a new PP system in place last season and it took them about 20 games to get used to it. After that they showed slow but steady improvement.

I checked out Driving Play and I like a lot of the insights. The preview of Flames was interesting.

I note the stats on “DZone Faceoff Shift Corsi Rate”. Basically, the Flames were one of the worst teams defensively, 5 on 5, off of Defensive Zone faceoffs. Other teams swarm us and dominate us with shot attempts etc. We give up more (per 60) in that situation than almost every other team.

Wouldn’t be surprised if this poor defensive play carried over to our penalty killing. Also wouldn’t be surprised if being trapped in our zone led to high percentage shooting opportunities for our opponents.

@tach – Unfortunately when I pull the PBP data I don’t record who scored the goal or took the shot, something I plan on doing in the future. The Flames made 19 of 129 shots, 14.7% with Babchuk on the ice on the PP and 40 of 293, 13.7% with him off. So it looks like there was about a one-percentage-point improvement in shooting percentage.

I may be wrong but didn’t the Flames start to put Tanguay in the QB position on the PP blue line in the 2nd half? My memory if fuzzy but i thought that look wasn’t trotted out until Daryl left. He probably would have had a stroke doing that due to the perceived defensive risk.